Competing Interests

The authors have declared that no competing interests exist.

Author Contributions

The author(s) have made the following declarations about their contributions: Conceived and designed the experiments: AS JAT JG FG AK. Performed the experiments: AS JAT JG MR FG AK. Analyzed the data: AS JAT JG FG HS AK. Contributed reagents/materials/analysis tools: TK. Wrote the paper: AS JAT AK. Conceived and designed the study: AK.